Groundwater interactions with surface-water systems greatly influence water quality characteristics such as cation, anion, nutrient, and dissolved organic matter concentrations, and even the fate and behavior of toxic pollutants.

For oil shale, says Wikipedia, environmental impacts include acid drainage induced by the sudden rapid exposure and subsequent oxidation of formerly buried materials, the introduction of metals into surface-water and groundwater, increased erosion, sulfur-gas emissions, and air pollution caused by the production of particulates during processing, transport, and support activities.

Otherwise, however, operational weather modifiers who want to have an effect on agriculture and surface-water supplies have to work with the far more dynamic environment of stacked and vertically developing clouds — which include thunderstorms and the infinitely chaotic mixtures of stratocumulus associated with frontal bands.

About 29 percent is discharged from the conterminous United States as surface-water flowing into the Pacific and Atlantic Oceans and across the borders into Canada and Mexico, about 2 percent is discharged as groundwater outflow, and about 2 percent is consumed by people, animals, plants, and used for industrial and commercial processes.

Thinking about the problem and the various difficulties — shallow fresh water getting infusions of old carbonate or decaying matter, etc. — it occurred to me to wonder whether there is a calcerous oceanic surface-water diatom one could use.